ATP Updates Production, Reserves, Developments and Financial Transactions

ATP Oil & Gas Corporation (NASDAQ: ATPG) today announced a recent production increase in 2010 of approximately 32% over the fourth quarter 2009 and a reserve replacement ratio of approximately 376% for 2009. In addition, ATP released updates on its 2009 production, year-end 2009 oil and gas reserves, development projects, recent acquisitions, monetizations and initial estimated CAPEX for 2010. ATP also outlined the terms of a recent amendment to its credit facility.

Production – ATP’s current producing rates are averaging between 17.0-19.0 MBoe/d, an increase of approximately 32% from production during the fourth quarter which averaged 13.6 MBoe/d. The increase is primarily due to a recompletion at Mississippi Canyon Block 711 ("Gomez”). Additional contributions to first quarter 2010 production levels are expected at Canyon Express and Telemark. Estimated production for 2009 was 3.4 MMBbls and 15.1 Bcf or approximately 5.9 MMBoe. Oil continues to comprise the majority of ATP’s production volumes representing 57% of total 2009 production volumes.

Reserves – Through performance driven volume revisions, extensions and discoveries, ATP added 22.1 MMBoe of proved reserves during 2009. ATP estimates year-end 2009 proved reserves of 135.2 MMBoe and a PV-10 value of $4.0 billion while year-end proved and probable reserves are estimated at 211.8 MMBoe and a PV-10 value of $6.4 billion using strip prices as of December 31, 2009. Since independent reservoir engineers are finalizing estimates of ATP’s oil and natural gas reserves for year-end 2009, ATP will issue its final reserve amounts utilizing SEC pricing and reconciliation in conjunction with filing its Form 10-K.

The Telemark Hub is now the largest property in ATP’s portfolio in terms of reserves with 49.3 MMBoe of proved reserves and 73.2 MMBoe of proved and probable reserves. At the Telemark Hub, ATP added 17.7 MMBoe of proved reserves and 31.4 MMBoe of proved and probable reserves during 2009. The significant reserve increase is primarily due to the favorable drilling results of the Mississippi Canyon Block ("MC”) 941 #3 well. ATP encountered 266 feet of logged hydrocarbons in the MC 941 #3 well or approximately three times the amount of net feet in the discovery well. ATP also recorded net increases in proved reserves at its Gomez Hub (MC 711, MC 755 and MC 754), Ladybug ("Garden Banks 409”) and Tors in the U.K. North Sea.

Development, Acquisitions and Monetizations

Telemark Hub – In the deepwater Gulf of Mexico, the ATP Titan is on location at MC 941 and final installation work is on schedule. The topside modules have been installed, all 12 mooring lines connected and the oil and gas export pipeline risers were installed and hydro-tested. Hookup and commissioning work is ongoing to prepare the facility to produce and process oil and gas. During the next few weeks, ATP is scheduled to finish connecting the pipelines and begin the dewatering process.

ATP continues active discussions with parties to explore opportunities to monetize ATP’s investment in the ATP Titan and other assets. During December 2009, ATP sold the deep exploratory rights below the productive horizons at MC 941 for an undisclosed amount resulting in a gain. ATP had no reserves booked or future development plans in the depths sold.

First production at Telemark remains on schedule for first quarter 2010. ATP concluded the initial phase of the planned activity of its three-well drilling campaign, two wells of which were drilled to a measured depth of approximately 12,000 feet and 13 5/8 inch casing was set at Mirage (MC 941) and Morgus (MC 942) which comprises two of the blocks that make up ATP’s Telemark Hub. ATP experienced outstanding results with the MC 941 #3 well and the additional pay sands added proved and probable reserves at the Telemark Hub at December 31, 2009. A third block within the Telemark Hub is Atwater Valley ("AT”) Block 63. The AT 63 #4 well is being completed with the Ocean Victory and will be connected as a subsea well to the ATP Titan through previously installed pipelines. The well has been perforated and gravel packed in three pay sands, and production tubing is being run. The Ocean Victory is expected to complete its work in February 2010. ATP owns a 100% working interest in the Telemark Hub and is the operator.

Canyon Express Hub - ATP also successfully completed and tested its Mississippi Canyon Block 217 #3ST2 well (part of Kings Peak and the Canyon Express Hub) in December 2009. ATP operates the MC 217 #3ST2 well and has a 55% working interest and expects to commence production from the well during the first quarter 2010.

Gomez Hub – ATP successfully commingled the 3750 B & C Sands in the MC 711 #4ST1 well using a dynamically positioned multi-purpose service vessel and a subsea riserless intervention system. After commingling the two reservoirs located between 11,400 feet measured depth and 11,900 feet measured depth, the commingled well is producing 9.0 MMcf/d and 4,900 Bo/d with a flowing tubing pressure in excess of 3,100 psi (4,600 Boe/d net). The successful commingling of the two reservoirs has set several deepwater intervention records that will be addressed in a later press release. MC 711 #4ST1 is part of the Gomez Hub where ATP operates and holds a 100% working interest in MC 711, MC 710, MC 755 and a 75% working interest at MC 754.

ATP continues to monetize its assets. ATP executed an asset sale agreement in October 2009 for net proceeds of $15.0 million for a dollar-denominated limited-term override in the Gomez Hub. On January 5, 2010, ATP closed a $135 million transaction pursuant to which ATP conveyed a limited term overriding royalty and a perpetual overriding royalty in MC 711, MC 754 and MC 755. The transaction was effective October 1, 2009. On January 26^th, ATP closed on an additional $5 million, effectively upsizing the original $135 million transaction to a total of $140 million.

In efforts to expand and consolidate interests in the Gomez Hub in January 2010, ATP consummated a like-kind exchange and an acquisition. Under the like-kind exchange ATP acquired an additional 50% working interest in MC 754, which increased ATP’s working interest to 75% and resulted in ATP’s designation as operator of MC 754. In 2008, the prior operator of MC 754 drilled an exploratory well that was drilled and cased and resulted in the discovery of the Anduin West field. ATP acquired the 50% MC 754 working interest in exchange for ATP’s 10% working interest in MC 800. In a separate transaction, ATP acquired a 100% working interest in MC 710 which is immediately adjacent to MC 711. The acquisition of MC 710 provides ATP with the opportunity to further expand the Gomez Hub. While these transactions removed 1.04 MMBoe of proved reserves associated with MC 800 at December 31, 2009, ATP expects to more than replace this reduction through its MC 754 acquisition.

Cheviot – Construction continues in China on the hull of the Octabuoy, a reusable floating production facility. The Octabuoy will service ATP's U.K. North Sea Cheviot property with first production scheduled in 2012. Approximately 58 MMBoe of remaining proved and probable reserves are expected at Cheviot. The hull for the Octabuoy is greater than 50% complete and remains on schedule for a 2011 sail out. ATP owns a 100% working interest in Cheviot and is the operator of the facility.

2010 Outlook – As progress continues towards first production from the AT 63 #4 well scheduled for first quarter 2010, ATP expects volume contribution from the Telemark Hub to result in more than doubling its 2009 company production in 2010. The remaining three wells at the Telemark Hub are scheduled to be brought on production sequentially during 2010. Other wells making contributions in 2010 are at Gomez, already placed on production in January, three wells in the Canyon Express Hub and potentially one well at the Tors project in the U.K. North Sea. Other wells and opportunities may be considered as the year progresses. The estimated CAPEX budget for 2010 is $572 million which includes both infrastructure development as well as the drilling and development program.

Recent Credit Agreement Amendment – On January 29, 2010, ATP and its Lenders amended the Credit Agreement associated with its Senior Secured Term Loan. The first piece of the amendment allowed ATP to recognize in its EBITDAX calculation for Credit Agreement purposes $123.1 million relating to economic gains associated with four previously completed monetizations. The four transactions will add $32.1 million in 1Q09, $35.8 million in 3Q09, $10.9 million in 4Q09 and $44.3 million in 1Q10 to ATP’s EBITDAX for Credit Agreement purposes. Each transaction resulted in cash being received by ATP, a reduction in ATP’s outstanding Senior Secured Term Loan and an economic gain to ATP that could not be recorded for GAAP purposes. The primary reason a gain could not be recognized for GAAP purposes was that ATP maintained a level of control or a continuing interest in the property after the monetization, a benefit to both ATP and its Lenders.

A second piece of the amendment expanded ATP’s ability to issue unsecured indebtedness which would be structurally junior to its outstanding Senior Secured Term Loan. The provision allows ATP the right to issue an unlimited amount of unsecured notes provided ATP uses at least 75% of the net cash proceeds to further reduce its Senior Secured Term Loan. This new provision allows ATP to continue to reduce its secured indebtedness by inserting a more permanent level of unsecured long-term capital into its capital structure.

ATP expects to be in compliance with its covenants associated with the Senior Secured Term Loan at December 31, 2009 and throughout 2010.

About ATP Oil & Gas Corporation

ATP Oil & Gas is focused on development and production of oil and natural gas in the Gulf of Mexico and the North Sea. The Company trades publicly as ATPG on the NASDAQ Global Select Market. For more information about ATP Oil & Gas Corporation, visit www.atpog.com.

Forward-looking Statements

Certain statements included in this news release are "forward-looking statements" under the Private Securities Litigation Reform Act of 1995. ATP cautions that assumptions, expectations, projections, intentions, or beliefs about future events may, and often do, vary from actual results and the differences can be material. Some of the key factors which could cause actual results to vary from those ATP expects include changes in natural gas and oil prices, the timing of planned capital expenditures, availability of acquisitions, uncertainties in estimating proved reserves and forecasting production results, operational factors affecting the commencement or maintenance of producing wells, the condition of the capital markets generally, as well as our ability to access them, and uncertainties regarding environmental regulations or litigation and other legal or regulatory developments affecting our business. The SEC has generally permitted oil and gas companies, in filings made with the SEC, to disclose only proved reserves that a company has demonstrated by actual production or conclusive formation tests to be economically and legally producible under existing economic and operating conditions. We and our independent third party reservoir engineers use the terms "probable" to describe volumes of reserves potentially recoverable through additional drilling or recovery techniques that the SEC's guidelines may prohibit us from including in filings with the SEC. These estimates are by their nature more speculative than estimates of proved reserves. All estimates of probable reserves in this news release have been prepared by management based on the preliminary December 31, 2009 reports of our independent third party engineers. PV-10 is a non-GAAP financial measure because it excludes income tax effects. Management believes that the presentation of the non-GAAP financial measure of PV-10 provides useful information to investors because it is widely used by professional analysts and sophisticated investors in evaluating oil and gas companies. PV-10 is not a measure of financial or operating performance under GAAP. The most directly comparable GAAP financial measure is the standardized measure of discounted future net cash flows. PV-10 should not be considered as a substitute for the standardized measure of discounted future net cash flows as defined under GAAP, which is calculated at year end under accounting rules by applying pricing assumptions of the SEC to our proved reserves. More information about the risks and uncertainties relating to ATP's forward-looking statements is found in our SEC filings.

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